Oracle-provided images have some unusual iptables rules by default, and need to be removed for nodes to work as expected.
They are in the iptables chain InstanceServices.
InstanceServices
To remove them, blank the files /etc/iptables/rules.v4 and /etc/iptables/rules.v6 and reboot.
/etc/iptables/rules.v4
/etc/iptables/rules.v6
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